#include "des.h"

uint8_t key[8] = {0xB4, 0x31, 0x5B, 0x86, 0x9D, 0x7D, 0xFA, 0xA2};
uint8_t data[8] = {0x1F, 0xAD, 0x61, 0xA5, 0xF7, 0x19, 0x77, 0x14};
uint8_t result[8];
const uint8_t initial_tr[64] = {
    57, 49, 41, 33, 25, 17, 9,  1, 59, 51, 43, 35, 27, 19, 11, 3,
    61, 53, 45, 37, 29, 21, 13, 5, 63, 55, 47, 39, 31, 23, 15, 7,
    56, 48, 40, 32, 24, 16, 8,  0, 58, 50, 42, 34, 26, 18, 10, 2,
    60, 52, 44, 36, 28, 20, 12, 4, 62, 54, 46, 38, 30, 22, 14, 6};
const uint8_t final_tr[64] = {
    39, 7, 47, 15, 55, 23, 63, 31, 38, 6, 46, 14, 54, 22, 62, 30,
    37, 5, 45, 13, 53, 21, 61, 29, 36, 4, 44, 12, 52, 20, 60, 28,
    35, 3, 43, 11, 51, 19, 59, 27, 34, 2, 42, 10, 50, 18, 58, 26,
    33, 1, 41, 9,  49, 17, 57, 25, 32, 0, 40, 8,  48, 16, 56, 24};
/*
const uint8_t swap[64] ={
        33, 34, 35, 36, 37, 38, 39, 40,
        41, 42, 43, 44, 45, 46, 47, 48,
        49, 50, 51, 52, 53, 54, 55, 56,
        57, 58, 59, 60, 61, 62, 63, 64,
         1,  2,  3,  4,  5,  6,  7,  8,
         9, 10, 11, 12, 13, 14, 15, 16,
        17, 18, 19, 20, 21, 22, 23, 24,
        25, 26, 27, 28, 29, 30, 31, 32
};
*/
const uint8_t key_tr1[56] = {
    56, 48, 40, 32, 24, 16, 8,  0,  57, 49, 41, 33, 25, 17, 9,  1,  58, 50, 42,
    34, 26, 18, 10, 2,  59, 51, 43, 35, 62, 54, 46, 38, 30, 22, 14, 6,  61, 53,
    45, 37, 29, 21, 13, 5,  60, 52, 44, 36, 28, 20, 12, 4,  27, 19, 11, 3};
const uint8_t key_tr2[64] = {0,  0,  13, 4,  16, 10, 23, 0,  0,  0,  2,  9,  27,
                             14, 5,  20, 0,  0,  22, 7,  18, 11, 3,  25, 0,  0,
                             15, 1,  6,  26, 19, 12, 0,  0,  40, 54, 51, 30, 36,
                             46, 0,  0,  29, 47, 39, 50, 44, 32, 0,  0,  43, 52,
                             48, 38, 55, 33, 0,  0,  45, 31, 41, 49, 35, 28};
const uint8_t etr[64] = {0,  0,  31, 4,  0,  1,  2,  3,  0,  0,  3,  8,  4,
                         5,  6,  7,  0,  0,  7,  12, 8,  9,  10, 11, 0,  0,
                         11, 16, 12, 13, 14, 15, 0,  0,  15, 20, 16, 17, 18,
                         19, 0,  0,  19, 24, 20, 21, 22, 23, 0,  0,  23, 28,
                         24, 25, 26, 27, 0,  0,  27, 0,  28, 29, 30, 31};
const uint8_t ptr[32] = {31, 14, 39, 44, 60, 23, 55, 36, 4,  30, 46,
                         53, 12, 37, 62, 21, 5,  15, 47, 29, 63, 54,
                         6,  20, 38, 28, 61, 13, 45, 22, 7,  52};
const uint8_t s[8][64] = {
    {14, 4,  13, 1, 2,  15, 11, 8,  3,  10, 6,  12, 5,  9,  0, 7,
     0,  15, 7,  4, 14, 2,  13, 1,  10, 6,  12, 11, 9,  5,  3, 8,
     4,  1,  14, 8, 13, 6,  2,  11, 15, 12, 9,  7,  3,  10, 5, 0,
     15, 12, 8,  2, 4,  9,  1,  7,  5,  11, 3,  14, 10, 0,  6, 13},
    {15, 1,  8,  14, 6,  11, 3,  4,  9,  7, 2,  13, 12, 0, 5,  10,
     3,  13, 4,  7,  15, 2,  8,  14, 12, 0, 1,  10, 6,  9, 11, 5,
     0,  14, 7,  11, 10, 4,  13, 1,  5,  8, 12, 6,  9,  3, 2,  15,
     13, 8,  10, 1,  3,  15, 4,  2,  11, 6, 7,  12, 0,  5, 14, 9},
    {10, 0,  9,  14, 6, 3,  15, 5,  1,  13, 12, 7,  11, 4,  2,  8,
     13, 7,  0,  9,  3, 4,  6,  10, 2,  8,  5,  14, 12, 11, 15, 1,
     13, 6,  4,  9,  8, 15, 3,  0,  11, 1,  2,  12, 5,  10, 14, 7,
     1,  10, 13, 0,  6, 9,  8,  7,  4,  15, 14, 3,  11, 5,  2,  12},
    {7,  13, 14, 3, 0,  6,  9,  10, 1,  2, 8, 5,  11, 12, 4,  15,
     13, 8,  11, 5, 6,  15, 0,  3,  4,  7, 2, 12, 1,  10, 14, 9,
     10, 6,  9,  0, 12, 11, 7,  13, 15, 1, 3, 14, 5,  2,  8,  4,
     3,  15, 0,  6, 10, 1,  13, 8,  9,  4, 5, 11, 12, 7,  2,  14},
    {2,  12, 4,  1,  7,  10, 11, 6,  8,  5,  3,  15, 13, 0, 14, 9,
     14, 11, 2,  12, 4,  7,  13, 1,  5,  0,  15, 10, 3,  9, 8,  6,
     4,  2,  1,  11, 10, 13, 7,  8,  15, 9,  12, 5,  6,  3, 0,  14,
     11, 8,  12, 7,  1,  14, 2,  13, 6,  15, 0,  9,  10, 4, 5,  3},
    {12, 1,  10, 15, 9, 2,  6,  8,  0,  13, 3,  4,  14, 7,  5,  11,
     10, 15, 4,  2,  7, 12, 9,  5,  6,  1,  13, 14, 0,  11, 3,  8,
     9,  14, 15, 5,  2, 8,  12, 3,  7,  0,  4,  10, 1,  13, 11, 6,
     4,  3,  2,  12, 9, 5,  15, 10, 11, 14, 1,  7,  6,  0,  8,  13},
    {4,  11, 2,  14, 15, 0, 8,  13, 3,  12, 9, 7,  5,  10, 6, 1,
     13, 0,  11, 7,  4,  9, 1,  10, 14, 3,  5, 12, 2,  15, 8, 6,
     1,  4,  11, 13, 12, 3, 7,  14, 10, 15, 6, 8,  0,  5,  9, 2,
     6,  11, 13, 8,  1,  4, 10, 7,  9,  5,  0, 15, 14, 2,  3, 12},
    {13, 2,  8,  4, 6,  15, 11, 1,  10, 9,  3,  14, 5,  0,  12, 7,
     1,  15, 13, 8, 10, 3,  7,  4,  12, 5,  6,  11, 0,  14, 9,  2,
     7,  11, 4,  1, 9,  12, 14, 2,  0,  6,  10, 13, 15, 3,  5,  8,
     2,  1,  14, 7, 4,  10, 8,  13, 15, 12, 9,  0,  3,  5,  6,  11}};
const uint8_t rots[16] = {1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1};
const uint8_t bit_msk[8] = {0x80, 0x40, 0x20, 0x10, 0x08, 0x04, 0x02, 0x01};
uint8_t DES_Encrypt_key[8];
uint8_t DES_Decrypt_key[8];
uint8_t sub_keys[16][8];
uint8_t main_key[8];
/************************************************************************/
/*                                                                      */
/*                      msb                     lsb                     */
/*                      bit                     bit                     */
/*                      +-- -- -- -- -- -- -- --+                       */
/*              addr    !1st                 8th!                       */
/*                      +-- -- -- -- -- -- -- --+                       */
/*              addr+1  !9th                16th!                       */
/*                      +-- -- -- -- -- -- -- --+                       */
/*                      :                       :                       */
/*                      :                       :                       */
/*                      +-- -- -- -- -- -- -- --+                       */
/*              addr+7  !57th               64th!                       */
/*                      +-- -- -- -- -- -- -- --+                       */
/*                                                                      */
/************************************************************************/
/****************************************************************************
* 名    称：void des(uint8_t *plain_strng, uint8_t *key, uint8_t d, uint8_t
*ciph_strng)
* 功    能：DES加密/解密函数：8字节的数据数组与8字节的密钥数组
* 入口参数：*plain_strng：待加密/解密的数据数组
                                                *key：用于加密/解密的密钥数组
                                                d：加密/解密的选择
0表示加密，1表示解密
* 出口参数：*ciph_string：加密/解密后的数据数组
* 说    明：无
****************************************************************************/
void des(uint8_t* plain_strng, uint8_t* key, uint8_t d, uint8_t* ciph_strng) {
  uint8_t a_str[8], b_str[8], x_str[8];
  uint8_t i, j, *pkey, temp;
  for (i = 0; i < 8; ++i) {
    if (key[i] != main_key[i]) {
      compute_subkeys(key);
      i = 7;
    }
  }
  transpose(plain_strng, a_str, initial_tr, 64);
  for (i = 1; i < 17; ++i) {
    for (j = 0; j < 8; ++j) {
      b_str[j] = a_str[j];
    }
    if (!d) /*enchipher*/
      pkey = &sub_keys[i - 1][0];
    else /*dechipher*/
      pkey = &sub_keys[16 - i][0];
    for (j = 0; j < 4; ++j) {
      a_str[j] = b_str[j + 4];
    }
    f(pkey, a_str, x_str);
    for (j = 0; j < 4; ++j) {
      a_str[j + 4] = b_str[j] ^ x_str[j];
    }
  }
  temp = a_str[0];
  a_str[0] = a_str[4];
  a_str[4] = temp;
  temp = a_str[1];
  a_str[1] = a_str[5];
  a_str[5] = temp;
  temp = a_str[2];
  a_str[2] = a_str[6];
  a_str[6] = temp;
  temp = a_str[3];
  a_str[3] = a_str[7];
  a_str[7] = temp;
  transpose(a_str, ciph_strng, final_tr, 64);
} /************************************************************************/
/*                                                                      */
/*      Module title:           transpose                               */
/*      Module type:            des subrutine                           */
/*                                                                      */
/*      Functional Description: Permute n bits in a string, according   */
/*                              to a table describing the new order.    */
/*                              0 < n <= 64                             */
/*                                                                      */
/*      input parameter 1:      pointer to first byte in input string   */
/*                      2:      pointer to first byte in output string  */
/*                      3:      pointer to table describing new order   */
/*                      4:      number of bits to be permuted           */
/************************************************************************/
void transpose(uint8_t* idata, uint8_t* odata, const uint8_t* tbl, uint8_t n) {
  const uint8_t* tab_adr;
  int i, bi_idx;
  tab_adr = &bit_msk[0];
  i = 0;

  do {
    odata[i++] = 0;
  } while (i < 8);
  i = 0;
  do {
    bi_idx = *tbl++;
    if (idata[bi_idx >> 3] & tab_adr[bi_idx & 7]) {
      odata[i >> 3] |= tab_adr[i & 7];
    }
  } while (++i < n);
}
/************************************************************************/
/*                                                                      */
/*      Module title:           rotate_l                                */
/*      Module type:            des subrutine                           */
/*                                                                      */
/*      Functional Description: rotate 2 concatenated strings of 28     */
/*                              bits one position to the left.          */
/*                                                                      */
/*      input parameter 1:      pointer to first byte in key string     */
/*                                                                      */
/************************************************************************/
void rotate_l(uint8_t* key) {
  uint8_t str_x[8];
  uint8_t i;
  for (i = 0; i < 8; ++i)
    str_x[i] = key[i];
  for (i = 0; i < 7; ++i) {
    key[i] = (key[i] << 1);
    if ((i < 6) && ((str_x[i + 1] & 128) == 128))
      key[i] |= 1;
  }
  if (str_x[0] & 0x80)
    key[3] |= 0x10;
  else
    key[3] &= ~0x10;
  if (str_x[3] & 0x08)
    key[6] |= 0x01;
  else
    key[6] &= ~0x01;
}
/************************************************************************/
/*                                                                      */
/*      Module title:           compute_subkeys                         */
/*      Module type:            des subrutine                           */
/*                                                                      */
/*      Functional Description: Computes the 16 sub keys for use in the */
/*                              DES algorithm                           */
/*                                                                      */
/*      input parameter 1:      pointer to first byte in key string     */
/*      output           :      fills the array sub_keys[16][8] with    */
/*                              sub keys and stores the input key in    */
/*                              main_key[8]                             */
/************************************************************************/
void compute_subkeys(uint8_t* key) {
  uint8_t i, j, ikey[8], okey[8];
  for (i = 0; i < 8; ++i) {
    main_key[i] = key[i];
  }
  transpose(key, ikey, key_tr1, 56);
  for (i = 0; i < 16; ++i) {
    for (j = 0; j < rots[i]; ++j) {
      rotate_l(ikey);
    }
    transpose(ikey, okey, key_tr2, 64);
    for (j = 0; j < 8; ++j) {
      sub_keys[i][j] = okey[j];
    }
  }
}
/************************************************************************/
/*                                                                      */
/*      Module title:           f                                       */
/*      Module type:            des subrutine                           */
/*                                                                      */
/*      Functional Description: The chipher function                    */
/*                                                                      */
/*      input parameter 1:      pointer to first byte in key string     */
/*                      2:      pointer to a 32 bit input string        */
/*                      3:      pointer to a 32 bit output string       */
/************************************************************************/
void f(uint8_t* skey, uint8_t* a_str, uint8_t* x_str) {
  uint8_t e_str[8], y_str[8], z_str[8];
  uint8_t k;
  transpose(a_str, e_str, etr, 64);
  for (k = 0; k < 8; ++k) {
    y_str[k] = (e_str[k] ^ skey[k]) & 63;
    z_str[k] = s[k][y_str[k]];
  }
  transpose(z_str, x_str, ptr, 32);
}
